Interrupters for spark-ignition



Jan. 17, 1956 E. w. DOWNING 2,731,523

INTERRUPTERS FOR SPARK-IGNITION APPARATUS Filed Feb. 11, 1952 United States Patent INTERRUPTERS FOR SPARK-IGNITION APPARATUS Eric William Downing, Handsworth Wood, Birmingham, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England Application February 11, 1952, Serial No. 270,958

Claims priority, application Great Britain February 21, 1951 2 Claims. (Cl. 200-31) This invention relates to the interrupters for use in conjunction with spark-ignition coils or magnetos, on vehicle engines, the interrupters being of the kind in which the ignition timing is automatically adjustable in response to variations of depression of pressure in the fuel inlet manifold of the engine.

The object of the invention is to enable such inter rupters to be variable also in response to variations of atmospheric pressure, it having been found advantageous to advance the ignition timing when travelling in mountainous country with increasing altitude.

The invention comprises the combination with an interrupter of the kind aforesaid, of a timing unit which is adapted to vary the timing in response to variations of the manifold depression of pressure, and which is itself spring loaded and is movable as a whole by depression of pressure in the manifold, the rest-position of the unit being determined by a stop under the control of an element responsive to atmospheric pressure.

The accompanying drawing is a sectional side elevation illustrating an embodiment of the invention.

In applying the invention as shown in the drawing, to an interrupter for use with an ignition coil, which interrupter includes a rotary cam a arranged to effect intermittent opening of spring loaded contacts I) mounted on an angular movable plate c surrounding the cam spindle d, there is provided in the housing e of the interrupter a hollow slidable member 1 which is loaded by a spring g and which at one end terminates in a chamber h. The latter is divided into two compartments by a diaphragm i which is loaded by a spring 1'. This chamber is contained in a larger chamber k on the housing, which is also divided into two compartments by a diaphragm m which may consist (as shown) of an extension of the first mentioned diaphragm. The compartment of the larger chamber k at one side of the diaphragm m is provided with a pipe connection 11 for effecting communication with the engine fuel inlet manifold, and the associated compartment of the smaller chamber has formed in its apertures 0 communicating with the said compartment of the larger chamber. The other two compartments are open to the atmosphere through apertures p, q.

To the centre of the diaphragm i in the smaller chamber is attached one end of a rod r which extends along the said slidable member 7 and is pivotally connected at the other end to the periphery of the plate c carrying the interrupter contacts.

The slidable member f, its associated chamber h, diaphragm i and rod r form a unit by which the ignition timing can be automatically varied in known manner in response to variation of the depression of pressure in the manifold. To enable the said unit to be moved as a whole for varying the timing in response to variations of atmospheric pressure, the hollow slidable member 1 is supported at one end by a wedge-shaped stop s arranged to be movable at right angles to the axis of the said memher 1, the latter being held in contact with the stop by the spring g acting on the said member. The stop is carried by one end of an elastic evacuated capsule t contained v in a chamber u on the housing in communication with the atmosphere through an aperture v.

To effect advancement of the ignition timing when ascending in a region of relatively high altitude, the driver momentarily closes the throttle of the fuel inlet manifold, and the consequent effect of the increased depression of pressure in the manifold acting on the part in of the diaphragm in the larger chamber k, causes the above described unit to be moved as a whole in opposition to the spring g and away from the stop s. The stop is then free to be moved by the capsule to a new position so that when the throttle is again opened the spring g returns the unit into contact with the stop at the new position which is in advance of the previous position. Thereafter, and until the driver again momentarily closes the throttle, variation of the ignition timing is effected by sliding movement of the rod 17 relatively to the member 1 in response to variation of the depression of pressure in the manifold acting on the part i of the diaphragm in the smaller chamher It, the spring g being sufiiciently strong to prevent the above described unit from being moved as a whole, by the said depression of pressure unless the throttle is closed. Each time the driver temporarily closes the throttle, at diiferent altitudes, the stop is also moved for changing the rest position of the unit. When descending to lower altitudes, the eifect of closing the throttle is to enable the air pressure acting on the capsule to withdraw the stop to an appropriate extent and so cause the unit to move in the direction for retarding the ignition timing.

By this invention adjustment of the ignition timing in response to both normal variations in the fuel inlet manifold and to variations of altitude can be effected in a very simple and satisfactory manner.

, Whilst in the example shown by the drawing, the invention is adapted for use with an ignition coil, it may be applied in essentially the same manner to a magneto.

Having thus described my invention What I claim as new and desire to secure by Letters Patent is:

1. An interrupter of the kind specified, comprising the combination of a hollow body part having a chamber at one end of it, an angularly movable member in the body part carrying the interrupter contacts, a spring-loaded slidable member in the body part, a stop for determining the rest-position of the slidable member, means responsive to atmospheric pressure for moving the stop, a chamher at one end of the slidable member and contained in the chamber on the body part, the two chambers being divided into two compartments by a single flexible diaphragm or by separate diaphragms, one compartment in each chamber being adapted for communication with the engine fuel-inlet manifold, and the other compartment in each chamber being in communication with the atmosphere, and a rod connecting the diaphragm in the second chamber to the angularly movable part carrying the interrupter contacts.

2. An interrupter of the kind specified comprising in combination mutually engageable contacts, a rotary cam for intermittently separating the contacts, a spring-loaded timing unit consisting of relatively movable parts, angularly movable means responsive to movement of the timing unit as a whole, and to relative movement of the parts of the timing unit, for varying the relative positions of the contacts and cam, and thereby varying the ignition timing of the engine, an adjustable stop against which the timing unit bears under its spring loading, and which serves to determine the position of the timing unit when the latter is at rest, means responsive to the manifold depression, of pressure for effecting relative movement of the parts References Cited in the file of this patent UNITED STATES PATENTS Doyen July 28, 1953 

